Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$161.40	3.873%	$167.651	$167.65	$167.65	$167.70
Purchase #2	$183.39	7.412%	$196.9829	$196.98	$197.00	$197.00
Purchase #3	$244.50	5.792%	$258.6614	$258.66	$258.65	$258.70
Purchase #4	$127.99	10.249%	$141.1077	$141.11	$141.10	$141.10
Purchase #5	$77.64	6.673%	$82.8209	$82.82	$82.80	$82.80
Purchase #6	$115.33	6.661%	$123.0121	$123.01	$123.00	$123.00
Purchase #7	$147.64	13.531%	$167.6172	$167.62	$167.60	$167.60
7 purchase totals =	$1,057.89		$1,137.8532	$1,137.85	$1,137.80	$1,137.90